The present invention relates generally to a anti-skid control system for use in motor vehicles to control the speed of each of the wheels of the motor vehicle so as to prevent locking of the wheels on a vehicle braking operation, and more particularly to such an anti-skid control system having a braking pressure control device associated in common with different wheels.
An approach taken currently in order to simplify the arrangement of anti-skid control system by controlling the braking pressures of separate wheels through a common braking pressure control device. An important problem in such an anti-skid control system is that the common braking pressure control device is required to choose between speeds of the separate wheels in execution of the anti-skid control and difficulty may be encountered to effect optical braking operations for both the separate wheels. One known way, as disclosed in Japanese Patent Provisional Publication No. 52-112093 (corresponding to GB 1581943), involves taking different wheel speed selections between the front side wheels and the rear side wheels. For example, the lower wheel speed is selected between the speeds of the front side wheels and the higher wheel speed is selected between the speeds of the rear side wheels. There is a problem which arises with such a way, however, in that, although one of the front side wheels will have an excellent braking efficiency due to provision of a sufficient braking force, the other of the front side wheels results in deterioration of the steering performance due to locking and further the braking efficiencies of both the rear side wheels are lowered due to unsufficient braking forces thereto. Thus, a further improvement would be required from the viewpoint of vehicle travelling stability in anti-skid control execution.